Shed Wiring

[Tezbedz]

Hi

I have looked at a couple of threads about supplying power to a shed for lighting and sockets, but, they seemed to degenerate into slanging matches about what is and is not legal and definitions thereof.

I have no wish to start that again, but, I would like to ask a question.

I want to provide power to a 8"x10" shed which is 3" from the side of the house.

I want to install a Fleurescent Lighting unit and 3 double sockets on a ring,
The shed will be used to house a Model Railway and apart from power to that there is a 200w frost protection heater and some tools (dremel,soldering iron)

I have a Garage consumer unit incoming RCCB with 2 MCB;s for lighting and socket circuits which I will install in the shed, then put in a ring for the sockets and install a basic lighting circuit, (junction box & switch).

I realisethis is cover by "P", but, would like to do the install or most of it myself.

Question 1: Can this be run as a spur from a socket on the outside wall of the house, through metal conduit 18" under the flags to the shed or should it come back to the consumer unit round the corner of the house.

Question 2: If as I suspect it need to come back to consumer unit would I be better replacing the present one with a better/bigger one. At present it has 4 circuit breakers with push buttons. (Not for me to install, I hasten to add)

Question 3: If I use a registered sparker who will certify work do I still need to notify building control.

I can't think of any other questions, but appreciate your advice so I know what to talk to the sparks about


Terry

 

[davy_owen_88]

I want to provide power to a 8"x10" shed which is 3" from the side of the house.

3 inches? Or do you mean feet (' = feet " = inches)? It is important to know the correct distance so we can chose a suitable cable.

I want to install a Fleurescent Lighting unit and 3 double sockets on a ring,
The shed will be used to house a Model Railway and apart from power to that there is a 200w frost protection heater and some tools (dremel,soldering iron)

I have a Garage consumer unit incoming RCCB with 2 MCB;s for lighting and socket circuits which I will install in the shed, then put in a ring for the sockets and install a basic lighting circuit, (junction box & switch).

The consumer unit will most probably come with a 6A and a 32A MCB hence the max. demand is 38A. This may seem high for what you intend to use but you want to have some extra capacity just in case and also to ensure discrimination with the MCB at the house.

Question 1: Can this be run as a spur from a socket on the outside wall of the house, through metal conduit 18" under the flags to the shed or should it come back to the consumer unit round the corner of the house.

You will need to run a length of SWA back to the consumer unit. Running off a spur is not good practice but if you don't use a consumer unit you could just fit a 13A fused spur at the house and then terminate the SWA to a metal socket in the shed and spur off that for the lights. Not the best method but it is a possibility if you are sure you don't need more than 13A of power at the shed.

Question 2: If as I suspect it need to come back to consumer unit would I be better replacing the present one with a better/bigger one. At present it has 4 circuit breakers with push buttons. (Not for me to install, I hasten to add)

Yes, you will need a spare way at the consumer unit for the feed to the shed.

Question 3: If I use a registered sparker who will certify work do I still need to notify building control.

No you do not need to notify BC if you use a sparky who is a member of a self-certification scheme.

Davy

 

[Tezbedz]

Sorry that is of course 3 FEET not 3 Inches.

I have got a Consumer unit, 40A 30mA RCCB B6/16A MCB.

The 6A will be for the lighting and 16A for sockets Model Railway only pulls 4A max, Heater is 200w therefore thats .8A so that leaves me a bit for the dremel and a 50W soldering Iron.

To summarise, although not best practise I should be able to run SWA from a fused spur in the dining room, and if I get a certified sparks to finish it off and test it I should be OK

I appreciate your help

Looking through this site there is a lot of good sound advice from a some very generous guys who give their opinions and help freely


Terry

 

[Adam_151]

Question 1: Can this be run as a spur from a socket on the outside wall of the house, through metal conduit 18" under the flags to the shed or should it come back to the consumer unit round the corner of the house.

A feed to a shed could come off an FCU on the ring depending on how much power is required, you have already stated you want a ring final in the shed, so back to the house DB with a submain is what you need in your case, remember the sockets in the shed need RCD protection, recommend you do this in a subboard in the shed, rather than in the house. SWA is the wiring method of choice in most cases, not steel conduit, btw

Question 2: If as I suspect it need to come back to consumer unit would I be better replacing the present one with a better/bigger one. At present it has 4 circuit breakers with push buttons. (Not for me to install, I hasten to add)

Very likely, sounds like an old wylex standard, assuming a TN system here...remember to tell your sparky you want the shed on the non-rcd side and you want RCD protection for the shed to be in the board in the shed

Question 3: If I use a registered sparker who will certify work do I still need to notify building control.

No, he will notify BC through his scheme registration (which just involves him filling out a basic online form and paying a few quid, there are no building inspectors involved*)


*although there is a slight chance the scheme he is registered on might want to inspect it with him when he renews his registration

I can't think of any other questions, but appreciate your advice so I know what to talk to the sparks about


Terry[/quote]

 

[Tezbedz]

A feed to a shed could come off an FCU on the ring depending on how much power is required, you have already stated you want a ring final in the shed, so back to the house DB with a submain is what you need in your case, remember the sockets in the shed need RCD protection, recommend you do this in a subboard in the shed, rather than in the house. SWA is the wiring method of choice in most cases, not steel conduit, btw

Ok I can appreciate that now, as I am fitting more than one socket I cannot take it as a spur.

Adam is "DB" the main consumer unit? I have the RCD protection on the subboard.

Looks like I need a new consumer unit and a much longer bit of SWA

Thanks

 

[Adam_151]

You can have as many sockets as you want on a 13A FCU as long as the load is not expected to be over 13A, however you stated you wanted a ring final in your shed, you'd have to take this to a DB and provide a 32A breaker, as its an outbuilding the only sensible thing to do would to have it going back to a board in the shed, and feed that from a submain from the house, and you are probably looking at a 40A submain, which is probably going to work out as needing 6mm² SWA (although its possible 10 might be required)

DB = Distribution Board, I generally use it interchangeably with the term CU to refer to a CU(though, I guess if we are being picky, then CU is just a special type of DB)

 

[davy_owen_88]

For 16A protection you don't need to make it a ring. A radial using 2.5mm² t&e will be plenty for your needs.

As you said you will only need about 1A for lights and 5A for power you can just take a spur from the ring main in the house and connect this to a 13A switched fused spur. From the load terminals take the feed to a metal adaptable box which you can terminate your SWA into. Run the SWA to the shed and terminate at a metalclad socket. Then just run the radial to the rest of the sockets and spur down with another switched fused spur with a 3A fuse for the lights.

A point to remember is that with this method you are limited to 13A for both sockets and lights.

For your small maximum demand I really don't see the point of running a new feed and fitting a CU when all you want is power for a train set and a soldering iron. Fitting the CU will require a larger cable so you can meet the discrimination issues, and will require a longer run to get back to the CU.

Davy